# Enhanced Biofuel Cells Based on a Hybrid Enzymatic/Bimetallic Composite for Complete Lactate Catalytic Electrooxidation

## TL;DR

A new hybrid electrode combining a bimetallic composite and an enzyme improves lactate oxidation in biofuel cells, leading to higher efficiency and complete conversion to CO2.

## Contribution

A hybrid enzymatic/bimetallic composite electrode is introduced, achieving complete lactate electrooxidation with enhanced catalytic performance.

## Key findings

- The hybrid electrode showed 2.0-fold higher catalytic activity than the bimetallic composite alone.
- The hybrid electrode achieved a 35% higher maximum current density and lower charge transfer resistance.
- Lactate was completely oxidized to CO2, harvesting all 10 electrons during the reaction.

## Abstract

We describe complete lactate electrooxidation in an enzymatic
biofuel
cell that combines the catalytic action of the bimetallic composite
Ru@Pt-CNT and the enzyme oxalate oxidase (OxOx). The Ru@Pt-CNT/OxOx
hybrid electrode was 2.0-fold more catalytically active than the electrode
containing the bimetallic composite only. During chronoamperometric
experiments, the hybrid electrode achieved a 35% higher maximum current
density (2.65 ± 0.15 mA cm–2) than the Ru@Pt-CNT
electrode. Electrochemical impedance spectroscopy showed that the
hybrid electrode had lower charge transfer resistance than the Ru@Pt-CNT
electrode, confirming that OxOx had a high affinity for lactate during
the bioelectrocatalytic reaction on the electrode surface. Furthermore,
18-h long-term bulk electrolysis revealed that lactate electrooxidation
at the Ru@Pt-CNT/OxOx hybrid electrode provided a total charge of
1.2 ± 0.2 C, which was 3-fold higher than the total charge generated
by the Ru@Pt-CNT electrode. The lactate oxidation products generated
at the hybrid electrode were detected during bulk electrolysis by
chromatography, which showed that the hybrid biofilm harvested all
10 electrons from lactate, completely oxidizing it to CO2. With exceptional stability and catalytic performance, the hybrid
electrode acted in the multiple catabolic steps of lactate oxidation.
Overall, the interaction between Ru@Pt-CNT and OxOx enhanced the assembly
of lactate biofuel cells to improve lactate electrooxidation. This
could pave the way for developing efficient electronic devices with
promising applications in bioelectrochemistry.